Induction heating (IH) electromagnetic field has a significant positive effect on the uniform temperature distribution in tundishes and decreases molten steel superheat to improve the quality of billets in continuous casting. To achieve the effect of electromagnetic force and Joule heating for molten steel in a channel-type IH tundish, a magnetohydrodynamic model is developed and validated by industrial experiment data. The molten steel in the tundish channel has a rotating velocity under the off-centre electromagnetic force. Its flow pattern consists of two contra-rotating vortices close to the outlet zone of the channels. The upper and lower vortices in the tundish channel change with time. The temperature distribution in the cross-sections is almost stable, and the maximum temperature increases by 30.1°C. Molten steel runs upward after flowing past the tundish channel, whose density decreases because of IH. The upward motion changes when the electromagnetic force acts on the molten steel. Results reveal that electromagnetic force has a significant effect on the flow of molten steel in the tundish, and that flow pattern varies in the tundish with or without electromagnetic force under Joule heating.

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Water inrush disasters poses a great threat to the safe exploitation of coal resources. To solve this problem, the transient electromagnetic method (TEM) was proposed to accurately detect the water accumulation in the goaf. The electromagnetic response characteristics of different water-filled goaves were studied by electromagnetic field theory, numerical simulation and field verification. Through the models of 100% water accumulation, 50% water accumulation, 0% water accumulation, 100% water accumulation with collapsed rock, 50% water accumulation with collapsed rock and 0% water accumulation with collapsed rock goaf, the characteristics of induced voltage attenuation curves were studied. Meanwhile, the relationship between the attenuation voltage value and area of the transmitting coil, the depth of the goaf, the background resistivity, and the delay time were also simulated. The results illustrate that the attenuation curve of induced voltage presented a regular exponential decay form in the 0% water accumulation model but existed abnormal exaltation for voltage in water-filled model. Through the linear fitting curve, it can be seen that the abnormal intensity of the induced voltage becomes stronger as the distance between the measuring point and the center of the target decrement. Moreover, the abnormal amplitude of the induced voltage increases with the rise of the water accumulation and collapsed rock will weakly reduce the low-resistivity anomalous effect on the water-accumulated goaf. In addition, the response value of the attenuation voltage increased as the area of the transmitting coil increases, but decreased with increasing delay time and increasing background resistivity and depth of the target body. The field detection results of the Majiliang coal mine also confirmed the theoretical analysis and the numerical simulation.